Characterising Draught in Mediterranean Multifamily Housing

Social housing dating from the postwar years through the end of the twentieth century is one of the major stores of European cities’ residential stock. As it is generally characterised by a poor thermal performance and an ine cient control of energy consumption, it constitutes one of the main targets for residential heritage renewal. This study aimed to locate and quantify air leaks across building envelopes in Mediterranean multifamily housing with a view to curbing the uncontrolled inflow of outdoor air that has a direct impact on occupant comfort and housing energy demand. Airtightness tests conducted in a series of protocols to quantify draught across envelope elements were supplemented with qualitative infrared thermographic and smoke tests to locate leakage pathways. Air was found to flow mainly across façade enclosures, primarily around openings, as well as through service penetrations in walls between flats and communal areas accommodating electrical and telecommunication wires and water supply, domestic hot water (DHW), and drainage pipes. The general absence of evidence of draught across structural floors or inter-flat partitions was consistent with the construction systems in place

Thermal Perception in Mild Climate: Adaptive Thermal Models for Schools

A comprehensive assessment of indoor environmental conditions is performed on a representative sample of classrooms in schools across southern Spain (Mediterranean climate) to evaluate the thermal comfort level, thermal perception and preference, and the relationship with HVAC systems, with a comparison of seasons and personal clothing. Almost fifty classrooms were studied and around one thousand pool-surveys distributed among their occupants, aged 12 to 17. These measurements were performed during spring, autumn, and winter, considered the most representative periods of use for schools. A new proposed protocol has been developed for the collection and subsequent analysis of data, applying thermal comfort indicators and using the most frequent predictive models, rational (RTC) and adaptive (ATC), for comparison. Cooling is not provided in any of the rooms and natural ventilation is found in most of the spaces during midseasons. Despite the existence of a general heating service in almost all classrooms in the cold period, the use of mechanical ventilation is limited. Heating did not usually provide standard set-point temperatures. However, this did not lead to widespread complaints, as occupants perceive the thermal environment as neutral—varying greatly between users—and show a preference for slightly colder environments. Comparison of these thermal comfort votes and the thermal comfort indicators used showed a better fit of thermal preference over thermal sensation and more reliable results when using regional ATC indicators than the ASHRAE adaptive model. This highlights the significance of inhabitants’ actual thermal perception. These findings provide useful insight for a more accurate design of this type of building, as well as a suitable tool for the improvement of existing spaces, improving the conditions for both comfort and wellbeing in these spaces, as well as providing a better fit of energy use for actual comfort conditions

Dynamic Daylight Metrics for Electricity Savings in Offices: Window Size and Climate Smart Lighting Management

Daylight performance metrics provide a promising approach for the design and optimization of lighting strategies in buildings and their management. Smart controls for electric lighting can reduce power consumption and promote visual comfort using different control strategies, based on affordable technologies and low building impact. The aim of this research is to assess the energy efficiency of these smart controls by means of dynamic daylight performance metrics, to determine suitable solutions based on the geometry of the architecture and the weather conditions. The analysis considers different room dimensions, with variable window size and two mean surface reflectance values. DaySim 3.1 lighting software provides the simulations for the study, determining the necessary quantification of dynamic metrics to evaluate the usefulness of the proposed smart controls and their impact on energy efficiency. The validation of dynamic metrics is carried out by monitoring a mesh of illuminance-meters in test cells throughout one year. The results showed that, for most rooms more than 3.00 m deep, smart controls achieve worthwhile energy savings and a low payback period, regardless of weather conditions and for worst-case situations. It is also concluded that dimming systems provide a higher net present value and allow the use of smaller window size than other control solutions

Impact of controlled ventilation systems on energy consumption in mediterranean school buildings

Current standards for indoor air quality (IAQ) in non-residential buildings demand high air renewal rates with different filtration stages and constant flow. Currently, new school buildings must incorporate mechanical ventilation systems which modify traditional heating installations in order to comply with the requirements for indoor air quality and energy efficiency. This study analyses the technical and energy outcomes involved in a school building when changing from a traditional central heating system with radiators, to an HV system which fulfils the current regulatory framework

Analysis of thermal emissions from radiators in classrooms in Mediterranean climates

Using computational fluid dynamics (CFD), this study focuses on the analysis of the thermal emissions of a typical classroom in an educational establishment in the south of Spain, and heated by radiators situated under the windows. It aims to study the way to exchange energy within the venue with this system. In order to do so a work methodology is developed which applies the Fanger method (PMV and PPD indicators) and the local thermal discomfort method to the isothermal curve sections generated by the CFD calculations, drawing up a series of lineal variation graphs on the temperature. This allows us to not only evaluate the degree of thermal comfort of the occupants in accordance with ASHRAE standards but also to carry out future comparisons between different thermal exchange system variants arising from the HVAC system. Following the application of this analysis the paper concludes that efficiency of the traditional radiator system to cope with the energy demand of the location is limited, given its incapacity to carry out a uniform exchange of energy between itself, the convective phenomena it generates, and the low relation between air volume/emitting surface, which translates into a lack of energy efficiency in the system, an aspect which is not usually contemplated in traditional analysis methods

Method for the Economic Profitability of Energy Rehabilitation Operations: Application to Residential Dwellings in Seville

This work proposes a method based on a computer model to assess the economic profitability of energy rehabilitation operations in the envelope of a block of residential dwellings (Virgen del Carmen) in Seville (Southern Spain). The work evaluates the influence that certain hypotheses of interventions in the opaque part of the envelope exert on the annual energy demand: better insulation of the façade, interior partitions, roof and ground floors, in addition to its semi-transparent part: improvements in the airtightness of the building openings, the glass windows, and the thermal conductivity of its frame. These interventions arise from strict compliance with the Spanish regulatory framework. This model has been designed for the context of a Mediterranean climate, (mild winters and hot summers). The simulation tool Design Builder 3.4.0.041, which uses the calculation engine Energy Plus 8.1, has been selected to generate the computing model and establish its energy demand. The amortization of the economic costs of rehabilitation is quantified by the net present value (NPV) index, in accordance with the savings in the bills of energy consumption due to the reductions in demand for heating and cooling in the building, thereby obtaining an amortization period which exceeds 22 year

Method for the Economic Profitability of Energy Rehabilitation Operations: Application to Residential Dwellings in Seville

This work proposes a method based on a computer model to assess the economic profitability of energy rehabilitation operations in the envelope of a block of residential dwellings (Virgen del Carmen) in Seville (Southern Spain). The work evaluates the influence that certain hypotheses of interventions in the opaque part of the envelope exert on the annual energy demand: better insulation of the façade, interior partitions, roof and ground floors, in addition to its semi-transparent part: improvements in the airtightness of the building openings, the glass windows, and the thermal conductivity of its frame. These interventions arise from strict compliance with the Spanish regulatory framework. This model has been designed for the context of a Mediterranean climate, (mild winters and hot summers). The simulation tool Design Builder 3.4.0.041, which uses the calculation engine Energy Plus 8.1, has been selected to generate the computing model and establish its energy demand. The amortization of the economic costs of rehabilitation is quantified by the net present value (NPV) index, in accordance with the savings in the bills of energy consumption due to the reductions in demand for heating and cooling in the building, thereby obtaining an amortization period which exceeds 22 year

Design and Performance of Test Cells as an Energy Evaluation Model of Facades in a Mediterranean Building Area

Abstract The current European energy policies have an influence on the need to rehabilitate the housing stock in order to meet the objectives of the European Union. Most of this housing stock was built without any type of energy regulation in adverse technical and economic conditions and thus is now energetically obsolete. The major rehabilitation effort required must be approached through actions based on previous quantitative energy knowledge of the existing buildings in order to guarantee the efficiency of energy-retrofitted solutions. This assessment can be carried out through monitoring dwellings conditioned by use patterns; through simulation programs, which do not usually offer faithful representations of energy conditions; or by using test cells, which allow us to evaluate a controlled indoor environment without the influence of users. The objective of this paper is to present the design and performance of test cells as an experimental method for vertical facade analysis in order to tackle the problem of retrofitting residential buildings in a Mediterranean climate, taking into account energy and environment. With this equipment, efficiency and energy savings, as well as illumination and interior air quality, can be simultaneously and comprehensively evaluated

CO2 Concentration and Occupants’ Symptoms in Naturally Ventilated Schools in Mediterranean Climate

A large part of the school building stock in Andalusia lacks ventilation facilities, so that the air renewal of the classrooms is achieved through the building envelope (air infiltration) or the opening of windows. This research analyses the airtightness of the classrooms in Andalusia and the evolution of CO2 concentration during school hours through in situ monitoring. Pressurization and depressurization tests were performed in 42 classrooms and CO2 concentration was measured in two di erent periods, winter and midseason, to study the impact of the di erent levels of aperture of windows. About 917 students (11–17 years of age) were surveyed on symptoms and e ects on their health. The mean n50 values are about 7 h-1, whereas the average CO2 concentration values are about 1878 ppm, with 42% of the case studies displaying concentrations above 2000 ppm with windows closed

URBAN LAYOUT FOR BUILDING SOLAR OPTIMIZATION AND OUTDOOR COMFORT BALANCE: NEIGHBORHOOD STRATEGY IN MEDITERRANEAN CLIMATE

The urban configuration in the Mediterranean area, which has noticeable solar radiation and significant thermal oscillation, is one of the factors that affect the microclimate and the urban heat island phenomenon of the cities located in that zone. To contribute to the improvement of urban comfort, this work presents an experimental methodological proposal for the analysis and multicriteria optimization of performance indicators using a parametric workflow through Grasshopper. This workflow can lead to the development of a set of environmental design criteria as support tools in the design of the urban configuration. The methodology is based on the quantification of two parameters on the analysis and management of daylight in interior spaces by means of dynamic metrics and, on the other hand, on the evaluation of hygrothermal conditions and the urban heat island effect, which affect both the daytime comfort of passersby and the nighttime comfort of dwellings. This study considers the most typical variables of urban layout, both morphological and material. The case study analyzed is located in the city of Seville (Spain), which has a significant percentage of its contemporary buildings without a suitable adaptation to local climate conditions. The results obtained from the case study prove the potential of the proposed methodology to evaluate and optimize lighting and thermal performance at the neighbourhood scale. Thus, it provides urban planners with a powerful decision support tool for both urban expansion and urban renewal